Sunday, November 9, 2014

vSphere Claim Rules with PowerCLI

We’ve been implementing HP 3PAR 7000 series into our environment. During this task we’ve tryied to be good admins by following the HP 3PAR StoreServ Storage and VMware vSphere 5 best practices.

Within this excellent resource there is a section for automating round robin policy for all 3PAR LUNs with a custom SATP rule.  That’s great, but it involves an esxcli command that must be run on each host:

For a small number of hosts that’s not too terrible--until you realize that you must either reboot each host or modify the policy for each LUN currently presented.  That’s not something that I’m likely to do.

With my aid of my technology buddy Google, I discovered several tidbits online:

  • Philip Sellers has a blog that works through much of this in PowerCLI.
  • Cormac Hogan has a blog that re-iterates the above, along with the commands required to unload each already claimed device (LUN), reload the claim rules, and rescan the HBAs.
Most of what I needed was out there already, of course. But I wanted to reload the claim rules in order to test the custom rule and without setting the policy individually on each LUN. I also didn’t want to impact every iSCSI LUN—just 3PAR—and there’s no need to reclaim a LUN that is already configured for round robin.

Here’s how I did it for each host:

Of course, I wrapped all of this around more PowerCLI that obtained a list of hosts in each cluster and managed the connections for esxcli.

If you receive any errors during the unclaim, make sure that your HA configuration is not using those LUNs as heartbeat datastores.  I experienced that problem which was easy to remedy in our environment.

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